W126 560vs500 injection systems

[jon_viola]

Can anyone tell me the differences?

Thanks

jon

 

[ray_hennig]

Your best bet might be to study the EPC using the appropriate w126.xxx references to see which parts differ, if any.

I have a W124.051 with the 6 cylinder M104 engine (similar technology to the 500/560 engines) and can tell you that the fuel system is different to that of the 6 cylinder M103 engine. Having said that, an M104 fuel distributor worked on an M103 engine when we tested briefly years ago. Fuel metering is a critical function so I should not be tempted to swap parts without careful measuring of what's really happening.

Sorry I can't be of more help.

 

[jon_viola]

Thanks for your reply.
I guess I'm looking at the fuel delivery system.

I've been told my car has the correct injectors but fuel octopus and inlet from a 500 not the 5.6.
Thanks

 

[carat 3.6]

Thanks for your reply.
I guess I'm looking at the fuel delivery system.

I've been told my car has the correct injectors but fuel octopus and inlet from a 500 not the 5.6.
Thanks

That shouldn't matter as long as they are adjusted properly.

 

[jon_viola]

Hi

when you say adjusted properly what do you mean? My car runs great idles more or less at the specified levels but really does feel short on power.

The system was set up by a well known Merc specialist after an engine rebuild Just before I bought the car and only around 2k miles ago.

is there anything that I should be looking at?

 

[carat 3.6]

Hi

when you say adjusted properly what do you mean? My car runs great idles more or less at the specified levels but really does feel short on power.

The system was set up by a well known Merc specialist after an engine rebuild Just before I bought the car and only around 2k miles ago.

is there anything that I should be looking at?

There is a lot involved in fine tuning a cis equipped engine, and most garages these days don't have the first idea what their looking at. A good idle on an engine that size is easy to get, even with it running out of spec.

You need to check for air leaks and ignition problems before you go anywhere near the injection system.

 

[jon_viola]

Thanks for your reply.
I have since discovered that perhaps the car is running a 500ecu too so will need to get that looked at.

So who near Sussex really knows there stuff about these engines?? Recommendations please.

 

[alabbasi]

The 500 motor was used through the life of the W126 from 1980-1991. The W126 can be split into 2 generations. Gen1 cars ran from 1980 to 1985 and Gen 2 cars from 1986-1991. The Gen 2 500 and 560 have the exact same fuel injection system which is called KE-Jetronic (CIS-E). They may have slightly different ignition systems (EZL) and the 560SEL would have an extra fuel pump.

The Gen 1 500 motor used CIS fuel injection which is 100% mechanical and uses a warm up regulator for enrichment.
In short, the differences between 86-91 cars in minor. The difference between 80-85 and 86-91 cars is major. If you're low on power, check the vacuum system which ties into the distributor advance. If not connected, or hooked up wrong, the car will feel low on power and also check if you're running on one fuel pump (if you own a 560)

 

[ray_hennig]

So who near Sussex really knows there stuff about these engines?? Recommendations please.

John Haynes in Worthing.

Do be aware that he does the job properly or not at all. So do have a healthy budget allocated.

RayH

 

[jon_viola]

The 500 motor was used through the life of the W126 from 1980-1991. The W126 can be split into 2 generations. Gen1 cars ran from 1980 to 1985 and Gen 2 cars from 1986-1991. The Gen 2 500 and 560 have the exact same fuel injection system which is called KE-Jetronic (CIS-E). They may have slightly different ignition systems (EZL) and the 560SEL would have an extra fuel pump.

The Gen 1 500 motor used CIS fuel injection which is 100% mechanical and uses a warm up regulator for enrichment.
In short, the differences between 86-91 cars in minor. The difference between 80-85 and 86-91 cars is major. If you're low on power, check the vacuum system which ties into the distributor advance. If not connected, or hooked up wrong, the car will feel low on power and also check if you're running on one fuel pump (if you own a 560)

Thanks for your reply.
So in essence if I've got the fuel pumps and ecu from the wrong car then although it'll run it'll be down on power which is what I'm experiencing.
The engines just been rebuilt and I've been round and checked for vacuum leaks so this would seem to be the issue.

At least fairly easy to sort!

This is the current installation. Twin inlet air intake going on this weekend.